Well, you should start by getting the latest template of
BibWord. There is also a guide there with information on how and what to format. Also looking at the other styles on this site, might help you get along the way.

If this is your first style you try to create, you could start from the Harvard - Exeter style and change that one.

In-text citations are pretty much formed as you want. The style does allow to show up to three authors for in-text citations before it is abbreviated to one author followed by 'et al.'. In your example you seem to stop at two. But that can easily done
by changing the value of "max_number_of_persons_to_display" from 3 to 2 in the appropriate namelist.

For the bibliography names are already displayed correctly. The only thing you might want to change here is the separator between names. In some cases, like before the last name, 'and' is displayed. But you can change that in the namelist for authors. For
the rest, you will pretty much have to order the elements in the different bibliography format strings the way you want. Only minor changes seem to be necessary.